D e t e c t i o n
NEO Photo-ionization detector
User Manual
D e t e c t i o n
8
Caution
During operation, make sure the probe inlet and the gas outlet are free of obstructions.
Obstructions can cause premature wear on the pump, false readings, or pump stalling.
5.4.1 PUMP STATUS
During normal operation, the pump icon alternately shows inflow and outflow. If there
is a pump failure or obstruction, the alarm sounds and the pump stall icon blinks on and
off. If this occurs, clear the obstruction and press the Right key to restart the pump.
5.5 EXTERNAL WATER-TRAP FILTERS
The external filter is made of a PTFE (Teflon) or PVDF membrane with 0.45 micron pore size to
prevent dust or other particles from being sucked into the sensor manifold, which could damage the
instrument. It prolongs the operating life of the sensor and pump. To install the external filter, simply
screw it in to the instrument’s inlet probe using the Luer connection.
5.6 ALARM SIGNALS
During each measurement period, the gas concentration is compared with the programmed alarm
limits (gas concentration alarm limit settings). If the concentration exceeds any of the preset limits,
the loud buzzer and red flashing LED are activated immediately to warn of the alarm condition. In
addition, the instrument alarms if one of the following conditions occurs: battery voltage falls below a
preset voltage level, failure of the UV lamp, or pump stall.
Message
Condition
Alarm Signal
HIGH
Gas exceeds ‘High Alarm’ limit
3 beeps/flashes per second
OVR
Gas exceeds measurement range
3 beeps/flashes per second
MAX
Gas exceeds electronics’ maximum range
3 beeps/flashes per second
LOW
Gas exceeds ‘Low Alarm’ limit
2 beeps/flashes per second
TWA
Gas exceeds ‘TWA’ limit
1 beep/flash per second
STEL
Gas exceeds ‘STEL’ limit
1 beep/flash per second
Pump icon flashes
Pump failure
3 beeps/flashes per second
Lamp
PID lamp failure
3 beeps/flashes per second plus ‘Lamp’
message
Battery icon flashes
Low battery
1 flash, 1 beep per minute plus battery icon
flashes
CAL
Calibration failed, or is overdue
1 beep/flash per second
NEG
Gas reading measures less than number
stored in calibration
1 beep/flash per second
Cal Gas
Cal Span
Unit
Low
High
TWA
STEL
Isobutylene
10
ppm
50
100
10
25
5.6.1 ALARM SIGNAL SUMMARY
5.6.2 PRESET ALARM LIMITS & CALIBRATION
The instrument is factory calibrated with standard calibration gas, and is programmed with default
alarm limits. For example, on the NEO PPM, the default values are:
